Antony Lerman falsely accuses me of calling for the "excommunication" of liberal lobby group J Street like the "Jewish apostates of the Middle Ages" who "fabricated blood libels". I have never proposed denying freedom of expression to groups hostile to Israel. I do, however, challenge J Street's duplicity in trying to masquerade as a Jewish mainstream "pro-Israel" organisation while consistently campaigning against the Jewish state. J Street represents a mere fringe group whose views are totally at variance with the attitude of the overwhelming majority of American Jews.

J Street policies are even more extreme than the most radical Israeli leftwing groups. The fighting with Hamas in Gaza, which was endorsed by all Jewish political parties in the Knesset, was criticised by J Street as "counterproductive" and "disproportionate". This, of itself, is no issue. What is unacceptable is the moral equivalency made by J Street between the policies of Israel and Hamas and its difficulty in distinguishing "between who is right and who is wrong".

It was recently disclosed that Arab and pro-Iranian elements were providing approximately 10% of J Street funding, a somewhat bizarre situation for a genuinely "pro-Israel" organisation. One donor and member of the organisation's finance committee, Genevieve Lynch, participated in the National Iranian American Council, the unofficial lobby group for the Iranian government. Judith Barnett, a former registered agent for Saudi Arabia, is a donor and serves on the J Street advisory council. Nancy Dutton, until 2008 an attorney for the Saudi Arabian embassy, donates to J Street's political action committees, which actively finance anti-Israeli congressional candidates.

In summary, J Street displays a consistent track record of hostility towards Israel. One has yet to see a single statement backing Israel on any substantive issue. It vigorously lobbies the US government to be "tough" to exert pressure on Israel's democratically elected government to make unilateral concessions. It opposes sanctions against Iran. It financially supports the election of anti-Israeli congressmen and raises the spectre of dual loyalties for American Jews who support Israel. In the process, it defames mainstream Jewish organisations, depicting them as extremists and misrepresents itself as a unique promoter of a "two-state policy" – despite the fact that a virtual consensus favouring this prevails among Israelis and diaspora Jews alike. It receives financial support and praise from foes of Israel. For an organisation of this nature to promote itself as "pro-Israel" is utterly preposterous.

Today the Jewish state is facing unprecedented pressures far beyond calls to freeze settlements. In the aftermath of the toxic Goldstone report, Israelis travelling abroad now face the threat of prosecution as war criminals, not least in Britain itself, where universal jurisdiction is cynically exploited by anti-Israel elements. Israel also faces the danger of a nuclear Iran. In these and other existential threats to Israel's very legitimacy and survival, Israel is largely dependent on US support, which J Street seeks to undermine.

No one seeks to deny critics of Israel freedom of expression. What is contemptible is the "pro-Israel, pro-peace" pretensions of J Street, reminiscent as they are of the Jewish communists who defended Stalin's state-sponsored Soviet antisemitism in the guise of promoting bogus "peace" campaigns.

The committed global Jewish community encompasses a wide range of opinions on many matters related to the Jewish state. However, it fervently supports Israel's broad struggle to defend its citizens against terror campaigns orchestrated by the mullahs of Iran through their surrogates, Hamas and Hezbollah. J Street is thus utterly dishonest when it lobbies the Obama administration to impose unilateral concessions on Israel, while misleadingly posing as speaking on behalf of the American Jewish mainstream. This is misrepresentation plain and simple.

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